This invention relates to a method of managing data for a storage system for archiving contents, in particular, unstructured fixed contents.
There are known many different data archive methods, any one of which has some shortcoming. Up until the recent past, the most commonly-used data archive method has used a tape archive. However, the tape archive is often hard to access, which prevents archived data from being retrieved quickly with ease. On this account, it becomes more common to select as an archive medium a disk array that allows access to the archived data quickly with ease.
A fixed content aware storage (FCAS) is generally defined by Storage Networking Industry Association (SNIA) as a storage of unchanging data (fixed contents) and metadata associated therewith based on a variety of naming schemas, and includes a content addressable storage (CAS) and global content-independent identifiers (see, for example, www.snia.org). In the storage industry, the CAS may be referred to also as “content addressed storage”, “content aware storage”, or “content archive storage”.
In the CAS, data is handled as an object composed of a file and metadata, rather than processed as a standard file. The data (file) is appended with the metadata (attributes of the file) and assigned a unique object identifier known as an “object ID”. For the data archive, the object is stored in any given location on a hard disk. U.S. Pat. No. 7,155,466 discloses a storage system and a data management method as an example of CAS implementation.